1. Field of the Invention
This invention relates generally to the collection of samples, and is specifically directed to capture of polymerase chain reaction- (PCR) ready DNA. The invention is directed to a system, structure, composition and method particularly useful in noninvasive extraction, facile processing and secure handling and storage of physical samples, including muccocutaneous cells.
2. State of the Art
A high-throughput, low cost, and reliable means of genomic DNA collection is required for research in molecular and genetic studies, as an alternative to collection and processing of blood samples. Buccal (cheek) swabs have been proposed as one approach to providing such means.
A recent study in Environmental Health Perspectives, Volume 107, Number 7, July 1999, provides information about the practical application of collection of genomic DNA by buccal swabs for polymerase chain reaction-based biomarker assays. From January 1995 to December 1997, under this study, 995 buccal swabs were processed for use in PCR-based genotype assays in the context of ongoing molecular epidemiologic studies. Six hundred forty-seven of these swabs were processed immediately after collection and 348 were received by mail. At least one genotype was obtained from 99.7% (645 of 647) of fresh-processed biosamples and from 97.4% (330 of 339) of mailed biosamples. A PCR success rate of 90.3% (2,5446 genotypes from 2,819 assays) was achieved. Genotypes were obtained from 96.1% (1,865 genotypes from 1,941 assays) of fresh-processed biosamples and 77.6% (681 genotypes from 878 assays) of mailed biosamples. PCR success rates at any single locus ranged from 92.6 to 98.8% (fresh-processed) and 75.5 to 79.6% (mailed). The PCR success rate among fresh-processed biosamples was significantly higher than among mailed biosamples, and more attempts were required to obtain a successful PCR result for mailed biosamples as compared to fresh-processed biosamples.
A practical application of DNA sample collection is disclosed as a part of a broader invention in U.S. Pat. No. 6,140,047 to Duff et al. “Method And Kit for Predicting Susceptibility To Asthma.” Duff et al. teach the benefits of early identification of genetic markers that indicate susceptibility to or increased risk of chronic obstructive airway disease, especially in children. Diseases of special interest in this regard are asthma, chronic bronchitis, emphysema and chronic bronchiolitis. Early detection facilitates aggressive treatment in early stages of disease. Genetic testing, also called genetic screening or genotyping, reveals mutations, or polymorphisms, in the nucleic acid of a patient that are indicative of either a cause of or increase in susceptibility to a disease state, or so-called linkage disequilibrium, within the patient's gene.
Linkage disequilibrium refers to the tendency of specific alleles to occur together more frequently than would be expected by chance. Alleles at given loci are in equilibrium if the frequency of any particular set of alleles (or haplotype) is the product of their individual population frequencies. While the cause of disequilibrium is often unclear, the fact of disequilibrium can be detected by genetic testing from suitable specimens of cells and DNA by means including, without limitation, blood, saliva and buccal swabs.
One method for treatment of biosamples, for example, according to Michael J. Kilborn, M.D., Ph.D., Clinical and Scientific Coordinator at Georgetown University Pharmacology Department, would include the following collection steps: (a) obtain a quantity of sterile (individually packaged) cotton swabs which can be placed dry into a clean/sterile container (sleeve, tube, jar or ziplock-bag); (b) if possible, have the patient swish water gently around his or her mouth, for a few seconds only, and spit it out (to remove any large food particles); (c) rub the tip of the swab firmly along the inside of the cheek of the patient, then seal the swab into its clean/sterile sleeve/tube/jar/bag; (d) to ensure an adequate amount of DNA is collected, therefore, at least three (3) and up to five (5) such swabs should be used to collect samples, as a result, step (c) should be repeated two to four times.
The following shipping steps should then be followed: (a) it is preferable that swabs be shipped immediately; (b) samples may be shipped at ambient temperature (no refrigeration or ice necessary); (c) the outside of shipping box/envelope should be labeled as follows: “Store at −20 degrees C. on receipt” and (d) state the address.
For storage purposes, if swabs can not be shipped immediately they should be stored at −20 degrees C. until they are shipped. Upon receipt, they will be stored again at −20 degrees C. until processed.
A commercial example of the foregoing method is embodied in the BuccalAmp™ DNA Extraction Kit distributed by Epicentre Technologies Corp of Madison Wis. According to the designated procedure a swab is rotated on the inside of the cheek, then rotated in a Quick Extraction™ DNA extraction solution within a vial, heated at 56 degrees C. for 30 minutes and 98 degrees C. for 15 minutes, rendering the DNA sample ready for PCR within the vial. This approach contemplates the use of a Catch-All™ sample collection swab which includes a soft foam swab on a flexible plastic handle. The porous foam is thought to capture more sample than standard buccal brushes and is described as easy and safe to use, even for pediatric sampling. These collection swabs are supplied individually in sterile hard plastic cylinders.
While the state of the art is characterized as an extremely easy and rapid method for extraction of PCR-ready genomic DNA from humans or small animals that eliminates the time and discomfort required for sample collection by blood draws, deficiencies in the foregoing methods art are evident.
Accordingly, the art suggests that adequate DNA for PCR-based applications can be obtained from buccal swabs, but that sampling or processing considerations may be important in obtaining optimal results. There is ample opportunity for improvement over the art in the specimen extraction processes, handling protocol and systems for effecting the same.
Prior specimen handling protocols include numerous steps, each juncture of which potentially allows for either inadvertent or intentional substitution of samples, introduction of contaminants in any given sample or confusion as to the substance or nature of the sample.
Heretofore there has been no system or method for extracting genetic markers from buccal (cheek) swabs in numbers sufficient to support multiple generation research. A need exists for such a system and method.
Furthermore there has been no known system that combines a buccal swab with a lid for storage of the swab within a vial and clean and minimal handling of the swab, both prior, as well as subsequent, to specimen extraction, including during shipment to and from the collection site.
There remains a need for such a multi-function vial, wherein the vial may be used for preservation of relative sterility of a buccal swab prior to specimen extraction; for facile retraction of the buccal swab from the vial for extraction of a specimen and contaminant-free return of the swab to the vial; for transport; for microcentrifuge processing; or for any or all of the foregoing.
Heretofore there has been no sample collection tip medium specifically suited to enhancing the attraction of the sought after sample to the tip. A need exists for such a tip medium.
There is yet an additional need for a system comprising a buccal swab, receivable by a vial having a compartment for storage of a composition, releasable into the vial, whereby specimen collection, protection, processing and storage is improved and facilitated.
A further need exists for a method of biosample handling that reduces the number of steps in the chain of custody.
Yet a further need exists for a composition suited to maintenance of a relatively sterile, microbe-free environment, within microcentrifuge-ready vials, during shipment to collection sites, or facilitation of debridement of specimen cells to be extracted, or use as a solvent to enhance recovery of a desired physical sample, or preservation of specimen cells or other physical samples after collection or after processing, or use as a reagent during processing of a physical sample.